For many years, fire hydrants of the "dry" barrel type have been constructed with brass nozzles inserted into a boss provided on a barrel of the hydrant, the brass nozzles being permanently retained in the boss by calking with lead or the like. In this respect, four inner locking lugs provided on the hydrant nozzle where given a fractional turn from slots in the boss of the barrel when installed and then calked with lead so that the nozzle could not be blown out with water pressure and likewise could not be removed from the hydrant barrel. Consequently, in such a hydrant construction, when it became necessary to replace a nozzle due to damage of the nozzle or wear of the hose threads on the nozzle, it was necessary to remove the entire hydrant barrel with the nozzle thereon and return it to the maintenance shop for repairs or modification.
More recently, hydrants have been constructed with replacement nozzles which could be replaced in situ merely by threading the nozzle out of the boss of the barrel and replacing the nozzle with another nozzle. While such a hydrant arrangment did require a machining operation to the cast iron barrel to provide threads therein, it did add utility to the hydrant in that it provided for quick repairs by maintenance crews of damaged nozzles. However, while this type of construction gave the hydrants considerable more utility from the standpoint of maintenance and also from the standpoint that it permitted change of hydrant nozzles when a community makes a change in size of hose connections, it was found that unauthorized personnel could merely unthread the nozzle from the hydrant barrel and thus the hydrant was not entirely satisfactory.
In order to prevent theft of the valuable brass nozzles and to make the hydrants completely foolproof, early efforts were made to lock the nozzle to the barrel. In this respect, after the nozzle was initially threaded into the boss on the hydrant barrel, radial holes were drilled through the boss and into the hydrant nozzle, and either a blind pin was radially inserted into the aligned holes or the hole in the boss was threaded and a threaded lock pin was inserted into the aligned holes. Although this arrangement functioned to prevent inadvertent removal of the nozzle, it had a drawback in that when it was desired to remove a nozzle for repair it required drilling out of the blind pin and when the nozzle was reinstalled, it was difficult to make the holes in the boss of the barrel and in the nozzle aligned for reception of the locking pin and still have proper torque. Additionally, if the nozzle was to be replaced with a new nozzle, it required drilling at the site of installation to provide a hole in the nozzle which aligned with the hole in the boss on the hydrant barrel.
In a more recent development of hydrants having means for locking replaceable nozzles to the bosses of the fire hydrants, the flange of the hydrant nozzle was provided with at least a portion of its peripheral surface spaced a predetermined distance radially inwardly from the wall of a counterbore in the boss and when the nozzle had been inserted into the boss with the proper torque, a self-tapping stainless steel screw was inserted between the peripheral wall of the counterbore and the peripheral surface of the flange, the screw preventing unthreading. While such an arrangement did increase the amount of torque necessary to remove the nozzle from the barrel, this torque could be overcome by application of a wrench to overcome the locking force of the screw since the threads of the screw were generally in a direction of a radial plane through and normal to the axis of rotation of the nozzle and thus, the threads of the self-tapping screw were not subjected to shear. Often times the screw would roll out when sufficient torque was applied to the nozzle.